7G BULLETIN 63, UNITED STATES NATIONAL MUSEUM. 



Avheii viewed obliquely from the side the normal marginal curve will 

 be seen and that in reality the pronotum is widest at the middle. 



It must also be borne in mind that the pronotal disc is normally 

 moderately declivous laterally in the present subgenus. 



In many sjiecimens (mostly male, but some females as well) the 

 pronotal sides are less strongly deflexed and appear quite evenly 

 rounded from apex to base, and as a result the pronotum is broader 

 as compared to those with strongly deflexed sides where the thorax 

 is less rounded and more narrowed to the base. 



Although the punctuation is variable, usually there is always some 

 evidence of a serial arrangement; rarely, the strial punctures are 

 rather large and even moderately impressed; these specimens ap- 

 ])roach (■orJ>on(nia in this respect, but om'issa is as a rule more elongate 

 in the male and more broadly ovate in the female. 



The strongly punctate individuals are not necessarily confined to 

 the region bounding the Colorado River on the west, but are to be 

 taken at any part of the distributional area. 



The larger Southern California specimens are to be referred to 

 ODiissa, as the characters exhibited by the anterior tibial spurs are 

 those characteristic of the i)resent section of the subgenus; with these 

 conceptions of omwm. and the elimination of qiiadr'u-ollis everything 

 becomes clear. 



Ampla is a larger, more elongate species wdtli elongate legs. 



For the differential characters of the varieties pygma'a and penin- 

 sularis see below. 



I am indebted to Prof. H. C. Fall for notes on comparisons of 

 specimens Avith the LeConte type. 



The mentum is variable, rather small to moderate in size, and tri- 

 angido-trapezoidal to trapezoido-parabolic ; surface rather strongly 

 j)unctate, more or less foveate laterally and convex at middle. 



The prosternum is convex or horizontal between the coxa^ and 

 nuicronate behind; the mucro may be small and subacute; larger and 

 conical in contour, or compressed and obliquely to nearly vertically 

 truncate behind. 



The mesosternum is more or less concave, and varies in the degree 

 of its obliquity. 



The intercoxal process of the abdomen is quadrate (male) or a 

 little transverse (female), and about a fifth (male) or a sixth (fe- 

 nuile) of its width Avider than the metasternal salient. 



The metasternum laterally between the coxa^ is as long as the width 

 of a mesotibia at the middle. 



The ])ost-coxal part of the first abdominal segment is equal (male) 

 or subequal (fenuile) in length to that of the process. 



In the male the second segment is about a half longer than the 

 third and twnce as long as the fourth, and equal to the length of the 

 process. 



